The U23-001 data logger supports the following measurements: Relative Humidity and Temperature

Temperature Sensor:

Operation range internal sensors: -40° to 70°C (-40° to 158°F)U23-002 external temperature sensor: -40° to 70°C (-40° to 158°F)U23-003 and U23-004 external sensors: -40° to 100°C (-40° to 212°F), with tip and cable immersion in fresh water up to 50°C (122°F) for one year

Accuracy: ±0.21°C from 0° to 50°C (±0.38°F from 32° to 122°F)Resolution: 0.02°C at 25°C (0.04°F at 77°F); see Plot A in the manual